BRDA 2025: Selected topics in (B)SM

29 Oct 2025, 10:00 → 30 Oct 2025, 18:00 Europe/Ljubljana

This workshop is intended to bring together and facilitate discussions between theorists working on various phenomenological aspects of the Standard Model and beyond. Topics include quark and lepton flavor phenomenology, top and Higgs physics, lattice QCD, machine learning approaches in HEP, high energy unification of quark and lepton matter, dark matter and astroparticle physics.

 

Wednesday 29 October

10:00 → 10:35 Shaikh Saad: Beyond Neutrino Mass: Observable $n$–$\overline{n}$ Oscillations in UV Complete Seesaw Models

Next-generation experiments like DUNE and NNBAR will greatly enhance sensitivity to neutron--antineutron oscillations, a direct probe of baryon number violation ($\Delta B = 2$) beyond the Standard Model. This talk discusses such oscillations in unified frameworks that also explain fermion and neutrino masses via seesaw mechanisms. Two scenarios will be discussed: (1) Type II seesaw with two color-sextet scalars, realizable in $SO(10)$/Pati--Salam models, and (2) Type III seesaw with a sextet scalar and color-octet fermion, naturally embedded in $SU(5)$. In both cases, the same dynamics linking fermion masses induces baryon violation, tying oscillations to flavor structure. Upcoming searches can probe new colored states up to $10^{11}$ GeV---far beyond collider reach---making $n$--$\overline{n}$ oscillations a rare low-energy window into grand unification and ultra-heavy new physics.

SAAD.pdf

10:35 → 11:00 Lovre Pavičić: Flavored color scalars for neutrino masses

Belica_Pavicic_v3.pdf

11:00 → 11:30 Coffee break

11:30 → 12:05 Ilja Doršner: On the doublet-triplet splitting problem

IJS2025_TALK_ID.pdf

12:05 → 12:40 Pietro Baratella: Thermodynamics from the S-matrix

brda_Pietro.pdf

12:40 → 13:05 Katarina Trailović: Stable Evaluation of Lefschetz Thimble Intersection Numbers: Towards Real-Time Path Integrals

BRDA_Trailovic.pdf

13:05 → 15:00 Lunch

15:00 → 15:35 Jonathan Kriewald: No track left behind

Belica2025.pdf

15:35 → 16:10 Patrick Bolton: Hunting for a light Z' portal to the dark side at Belle II'

patrickbolton_talk_belica.pdf

16:10 → 16:40 Coffee break

16:40 → 17:15 Amelia Drew: Axion String Source Modelling

Axion strings are topological defects that arise in particle physics models with a spontaneously broken global U(1) symmetry, motivated, for example, by the Peccei-Quinn mechanism. They are predicted to emit massless axions, massive particles and gravitational waves. If we are to detect axion dark matter in the post-inflationary symmetry breaking scenario, understanding the spectrum of the axions emitted from a network of strings will be crucial. I will detail my work modelling the dependence of axion string radiation on the string curvature using adaptive mesh refinement simulations, reconciling with Nambu-Goto effective action predictions.

Ljubljana_2025_Drew.pdf

17:15 → 17:50 Takuya Okawa: Probing the Dirac-Majorana nature of neutrinos

The question of whether neutrinos are Dirac or Majorana remains open. This is mainly because almost all of the accessible neutrinos, such as laboratory neutrinos and neutrinos of astrophysical origin, are ultra-relativistic, erasing signatures that distinguish Dirac from Majorana neutrinos. We thus consider heavy neutrinos and discuss the possibility of distinguishing their Dirac versus Majorana nature. In particular, we allow a heavy neutrino to decay into another neutrino and an intermediate particle, which subsequently decays into the Standard Model particles. Then, we analyze the angular distribution of decay products for both Dirac and Majorana heavy neutrinos.

2025_BRDA_Okawa.pdf

18:30 → 21:30 Dinner

Thursday 30 October

10:00 → 10:35 Zachary Polonsky: (B)eyond the Anomalies

BRDA_Polonsky.pdf

10:35 → 11:00 Ivan Vujmilović: Electromagnetic form factors and structure of the T_{bb} tetraquark from lattice QCD

brda_vujmilovic.pdf

11:00 → 11:30 Coffee break

11:30 → 11:55 Lovro Dulibic: Nonperturbative contributions of QCD condensates to DDbar mixing

A naive leading-order perturbative calculation of the charm meson mixing parameters falls short of the experimental values by several orders of magnitude. This discrepancy arises from the Glashow-Iliopoulos-Maiani (GIM) mechanism, which strongly suppresses the leading contributions. Higher-order corrections, nonperturbative effects, and possible BSM effects can lift this suppression through flavour SU(3) breaking. In this work, we investigate the nonperturbative long-distance contributions arising from QCD condensates, incorporating for the first time the effects of mixed and four-quark condensates. Our results show an improvement in the predicted mixing parameters by up to two orders of magnitude compared with the perturbative NLO result, providing valuable insights into nonperturbative QCD dynamics. Although our estimates remain below experimental measurements, this study represents an important step toward narrowing the gap between theory and observation - an essential step in assessing potential contributions from BSM physics.

brda2025dulibic.pdf

11:55 → 12:20 Nikiša Plešec: Indirect Constraints on Higgs-mediated FCNCs

slides_Plesec.pdf

12:20 → 12:55 Rafal Maselek: Machine learning the likelihoods

RMaselek.pdf

12:55 → 14:55 Lunch